This invention relates in general to antifriction bearings and more particularly to a bearing arrangement that is unitized or held together by an end closure, such as a seal, and to a seal for such a bearing arrangement.
It has long been the practice for bearing manufacturers to supply railroad bearings in a unitized, preset, prelubricated, and sealed condition. This enables the bearing to be easily installed on an axle journal, for in doing so one need not be concerned with adjusting the bearing, keeping track of its multitude of parts, or adding lubricant to it. The typical railroad bearing of the tapered roller variety has a double cup (outer race) and a pair of cones (inner race) which are separated by a spacer sleeve. Tapered rollers are arranged in two rows between the raceways of the cup and the cones, and these rollers are held around the cones by cages, even when the cones are withdrawn from the cup. The whole arrangement is unitized for handling purposes by seal cases which are secured to the ends of the cup and prevent the cone assemblies from moving out of the cup. A typical railroad bearing of the type manufactured by The Timken Company is illustrated as U.S. Pat. No. 3,494,682.
One method of securing the seal cases is to merely force them into the ends of the cup with a press fit. To enhance the retention each seal case is normally provided with locking bead that projects into an undercut in the bore into which the seal case is pressed. Even so conventional seal cases can on occasion work loose as their ability to be retained in the bearing cup is limited.
With the advent of front wheel drive automobiles, automobile manufacturers have discovered that many of the principles incorporated into tapered roller railroad bearings are equally desirable in the front wheel bearings for their automobiles. In this regard, front wheel drive automobiles are generally lighter than their rear wheel drive counterparts, but most of the weight is concentrated over the front wheels, indeed, significantly more than in a comparable rear wheel drive automobile. This makes tapered roller bearings ideally suited for front wheel drive automobiles because such bearings are capable of carrying high radial loads as well as substantial thrust loads--all with a high degree of stability.
Automobile manufacturers find it convenient to have the bearings preset and also unitized for handling purposes, since this facilitates the assembly of their front wheel units. Moreover, some manufacturers want the bearings to remain together even when the nut and stub shaft that normally clamp the two cones together are removed, this to prevent the inboard cone from walking off of the hub spindle, so to speak, under the induced load caused by the taper of the rollers. Others want to be able to strip the cones from the hub spindle over which they are pressed without having the entire bearing come apart.
Whatever the reason, it is in some automotive applications desirable to unitize the bearings not only to the extent that they will remain together for handling purposes, but further to the extent that they will remain unitized when their cones are subjected to substantial parting forces. Conventional press fits, even when supplemented with locking beads, do not provide the retention necessary to meet these requirements.